Preparation And Properties Of Graphene/Metal Oxides Gas Sensitive Materials

With the fast development of the industrialization,more and more toxic and harmful gases are released into the atmosphere.Therefore,we need to monitor these gases to protect our lives and property.Gas sensing materials are the core components of gas sensors.The most commonly used gas sensing materials are metal oxides.However,single metal oxides always suffer from the disadvantages of low sensitivity and slow response.In recent years,graphene has been widely used in the manufacture of energy storage devices and sensing materials since the finding due to its excellent electrochemical properties.The combination of graphene and metal oxides can effectively improve the properties in the applications of gas sensing.This paper discusses the synthesis of grapheme/metal oxide materials by various methods,and explores their gas sensing mechanism.Here are the main works in this paper:Reduced graphene oxide decorated rice-like?-Fe₂O₃ was successfully fabricated via a facile two step hydrothermal process.We investigate the morphological and crystal structure through several characterization techniques,including SEM,XRD and XPS,and designed experiments to exploring the effects of reaction temperature,reaction time and other conditions on the morphology of the product.The?-Fe₂O₃ exhibited rice-like morphology and the rGO nanosheets distributed discretely on their surface.Through the gas sensing performance test,we found that the rGO/?-Fe₂O₃ showed higher substantial response to acetone,and the sensors also exhibited pretty good reproducibility and long-term stability.A series of the rGO decorated hollow Co3O4 spheres were fabricated via a solvothermal-calcination process.And we explored the effect of the additon amount of rGO on the gas sensitivity of the material.The as-synhesized hollow Co₃O₄ microspheres were assembled by nanoparticles with an average diameter of 25 nm with good crystallinity and adhered uniformly on rGO nanosheets.According to the gas sensing test,3 wt%rGO/Co₃O₄ hollow spheres showed a higher substantial response to ethanol.In addition,it also exhibited short response-recovery time and good reproducibility.A series of Ag/ZnSnO₃/rGO were obtained by coprecipitation method and modifying different amounts of elemental silver on the surface.The material exhibited cubic morphology with the particle size of 1?m.Some graphene sheets wrapped around the surface,and others strenched between two cubes forming a"bridge"structure.The silver particles were evenly distributed with good dispersibility.The gas sensitivity test showed that the Ag/ZnSnO₃/rGO exhibited beetter gas sensing performance compared with the undecorated samples.At last,we discussed the mechanism of improving sensing properties of rGO and silver.